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Biomedical subjects

M Gotoh

Publications and source records attributed to M Gotoh.

At least 145 records · Page 8Linked to original sources
PubMed1997

Quasiperiodicity and chaos in cardiac fibrillation.

In cardiac fibrillation, disorganized waves of electrical activity meander through the heart, and coherent contractile function is lost. We studied fibrillation in three stationary forms: in human chronic atrial fibrillation, in a stabilized form of canine ventricular fibrillation, and in fibrillation-like activity in thin sheets of canine and human ventricular tissue in vitro. We also created a computer model of fibrillation. In all four studies, evidence indicated that fibrillation arose through a quasiperiodic stage of period and amplitude modulation, thus exemplifying the "quasiperiodic transition to chaos" first suggested by Ruelle and Takens. This suggests that fibrillation is a form of spatio-temporal chaos, a finding that implies new therapeutic approaches.

Action Potentials↗
PubMed1997

Intrinsic healing capacity and tearing process of torn supraspinatus tendons: in situ hybridization study of alpha 1 (I) procollagen mRNA.

To determine the healing potential and healing process of torn supraspinatus tendons, in situ hybridization was used to localize cells containing alpha 1 type-I procollagen mRNA. Biopsy specimens of torn supraspinatus tendons from 19 patients with complete-thickness tears and 13 patients with incomplete-thickness tears were obtained during surgery. Four macroscopically normal supraspinatus tendons were obtained to serve as normal controls. Specimens were fixed in 10% buffered formalin and embedded in paraffin. A 22-mer oligonucleotide probe was labeled with digoxigenin and used as an in situ marker. The labeled cells were mainly composed of tenocytes and undifferentiated mesenchymal cells. In complete-thickness-tears, the labeled cells at the proximal tendon-stumps in the specimens that were obtained less than 4 months after trauma were significantly more abundant than in the specimens obtained 4 months or more after trauma. However, the number of labeled cells was maintained at the torn portion even in long-standing incomplete-thickness tears. The labeled cells at the margins of concomitant intratendinous extensions of the tears were detected even in the long-standing tears. The intratendinous extensions exhibited more labeled cells than the bursal-side or joint-side layers of the tendon substance in the incomplete-thickness tears (p < 0.05). The torn supraspinatus tendon may possess an intrinsic healing capability in the intermediate and late phases of tendon healing. Incomplete-thickness tears and concomitant intratendinous extensions can continue to rupture after the initial injury.

Adult↗
PubMed1997

Significance of granulation tissue in torn supraspinatus insertions: an immunohistochemical study with antibodies against interleukin-1 beta, cathepsin D, and matrix metalloprotease-1.

The pathophysiology of rotator cuff tears can be elucidated by examining the tendinous insertion of the supraspinatus muscle. As seen by light microscopy, the granulation tissue around the insertion of a torn supraspinatus tendon appears to induce osteochondral destruction by means of multinucleated giant cells and chemical mediators. The purpose of this study was to examine the contribution of certain chemical mediators to osteochondral destruction using immunohistochemical analysis of interleukin-beta, cathepsin D, and matrix metalloprotease-1. Sixteen supraspinatus insertions with portions of the greater tuberosity, including eight complete-thickness tears and eight incomplete-thickness tears, were obtained during surgery. Six fresh cadaveric supraspinatus tendons without grossly evident tears served as normal controls. Strong immunoreactivity was found in all 16 torn supraspinatus insertions but not in the six insertions of apparently intact tendons. Macrophages and multinucleated giant cells, which showed immunoreactivity for all three chemical mediators, were often found at the interface between the osteochondral margin of the enthesis and the granulation tissue, suggesting that they may be involved in osteochondral destruction. We therefore concluded that, in addition to repetitive subacromial impingement, this granulation tissue may contribute to the development of rotator cuff tears by weakening the insertion.

Adult↗
PubMed1997

Prostacyclin analog-suppressed ischemia-reperfusion injury of the rat liver: evaluation by calpain mu activation.

Prostaglandin I2 has a protective effect on hepatic ischemia-reperfusion injury. However, the exact intracellular mechanisms of this effect have not been elucidated. Calpain micro, a Ca2+-dependent protease, has been found to play a role in the ischemia-reperfusion injury of various organs. The hilar area of the left lateral and median lobes of rat livers was clamped for 60 min. A prostaglandin I2 analog (OP2507, C35H41NO4) was intravenously administered at 0.1, 0.32, or 1.0 microg/kg/min from 20 min before the ischemia. In addition to biochemical and microscopic analyses, the activation of calpain mu was investigated using specific antibodies against the intermediate (activated) and preactivated forms of calpain mu. The degradation of talin was also studied by Western blotting. When OP2507 was infused at 0.32 and 1.0 microg/kg/min, bile flow significantly increased after reperfusion compared with the control group, consistent with the decrease in serum transaminase levels. Membrane bleb formation and the appearance of the intermediate form of calpain mu were observed at 60 min of ischemia in the control and OP2507 (0.1 microg/kg/min) groups and remained present until 120 min after reperfusion. OP2507 (1.0 microg/kg/min) markedly suppressed not only membrane bleb formation but also calpain mu activation and the degradation of talin. In conclusion, OP2507 suppresses ischemia-reperfusion injury of the rat liver, and its cytoprotective effect is closely associated with the inhibition of calpain mu activation.

Alanine Transaminase↗
PubMed1997

New endoscopic treatment for chronic pancreatitis, using contrast media containing ulinastatin and prednisolone.

The preventive effects of contrast media containing ulinastatin (UST) and/or prednisolone (PDN) on potential complications associated with endoscopic retrograde cholangiopancreatography (ERCP) were studied in 111 patients. The incidence of abdominal pain and the elevation in the serum amylase level after ERCP were lower in the UST group than in the control group and abdominal pain and the elevated serum amylase level were almost completely suppressed in the PDN and UST/PDN groups. Based on these findings, a comparative study was conducted to evaluate the effectiveness of a combination of UST and PDN, given via the pancreatic duct, in alleviating pain symptoms in 57 patients with chronic pancreatitis and abdominal pain. The post-ERCP serum amylase level in some patients in the PDN and UST/PDN groups was lower than the pretreatment value. After ERCP, the abdominal pain that had been experienced before ERCP was relieved, and the value of the bentiromide-paraaminobenzoic acid (BT-PABA) test had improved. These results suggest that the use of contrast media containing PDN or UST/PDN in patients with chronic pancreatitis is extremely effective not only for preventing potential complications related to ERCP but also as a new diagnostic treatment method.

Abdominal Pain↗
PubMed1997

Bladder neck support prosthesis: a nonoperative treatment for stress or mixed urinary incontinence.

PURPOSE: We evaluated the usefulness and safety of a bladder neck support prosthesis in patients with stress or mixed incontinence. MATERIALS AND METHODS: A total of 57 women with stress and 20 with mixed incontinence completed a 12-week prospective clinical trial of a bladder neck support prosthesis. While indexes of incontinence episodes, leakage amounts and urgency along with a bothersome index were subjectively evaluated, a 60-minute pad test and urinary flow parameters were objectively evaluated. Three patients scheduled to undergo surgery for stress incontinence voluntarily used the device, and provided urodynamic data and cystourethrograms. Two prongs at 1 end of the ring, a type of elastic vaginal pessary, elevate the bladder neck against the pubic bone and facilitate pressure transmission around the bladder neck, resulting in urinary continence. RESULTS: Four subjective indexes significantly improved. There was no urinary flow obstruction. Urine loss decreased from 20.6 to 4.8 gm. per hour (p < 0.001) on the 60-minute pad test. Of the patients 22 (29%) reported complete continence and 39 (51%) had decreased severity of incontinence by more than 50%. Minor adverse effects occurred in 26% of the patients. Taking subjective evaluation, changes in objective parameters and adverse effects into consideration, 62 patients (81%) had some or maximum benefit according to the global usefulness rating. CONCLUSIONS: The bladder neck support prosthesis is safe, well tolerated and clinically effective for the treatment of stress or mixed incontinence.

Adult↗
PubMed1997

Effect of acidotic challenges on local depolarizations evoked by N-methyl-D-aspartate in the rat striatum.

We have examined how various challenges to brain acid-base homeostasis, resulting in extracellular acidosis, alter N-methyl-D-aspartate (NMDA)-evoked depolarizations in vivo. Repeated stimuli were produced by perfusion of 200 microM NMDA for 2 min through a microdialysis probe implanted into the striatum of halothane anesthetized rats. Hypercapnia reduced NMDA-evoked responses in a concentration-dependent manner, with 7.5 and 15 % CO2 in the breathing mixture reducing the depolarization amplitude to 74 % and 64 % of that of the initial stimuli, respectively. Application of 50 mM NH4+ progressively reduced dialysate pH, and a further acidification was observed when NH4+ was discontinued. Perfusion of NMDA after NH4+ application evoked smaller depolarizations (56 % of the corresponding control, 5 min after NH4+ removal), and this effect persisted for over 1 h. Perfusion of acidic ACSF did not alter the amplitude of NMDA-evoked depolarization, despite changes in dialysate pH confirming that exchange/buffering of acid equivalents took place between the perfusion medium and the surrounding tissue. This negative result probably reflected the remarkable capacity of the brain to buffer H+. Together, these results demonstrate that extracellular acidosis, such as that associated with excessive neuronal activation or ischemia, inhibits NMDA-evoked responses in vivo.

Acid-Base Equilibrium↗
PubMed1997

Anti-endothelial cell antibodies to the endothelial hybridoma cell line (EAhy926) in systemic lupus erythematosus patients with antiphospholipid antibodies.

The endothelial hybridoma (EAhy926) cell line was employed to clarify whether antiphospholipid antibodies (aPA) [lupus anticoagulant (LA), antiprothrombin antibody (aPT) and/or anticardiolipin antibody (aCL)] and anti-endothelial cell antibodies (AECA) are identical, and establish whether beta2-glycoprotein I (beta2-GPI) is needed for reactivity of aPA to endothelial cells. Ig-G AECA was positive in 9/30 SLE patients with aPA (30.0%) and 10/22 SLE patients negative for aPA (45.5%). Ig-M AECA was positive in one SLE patient with aPA and one SLE patient without aPA. AECA-positivity was not significantly different among unfixed, TNF-stimulated and fixed EAhy926. The influence of beta2-GPI on the reactivity of serum to EAhy926 was minimal, and absorption experiments of serum with cardiolipin-liposome/beta2-GPI or phosphatidylserine-liposome/prothrombin gave little evidence of cross-reactivity of aPA and AECA. The results of our study suggest that aPA and AECA may have partially cross-reacted, but were different antibodies. However, further study is needed to clarify the clinico-pathological significance of AECA.

Antibodies↗
PubMed1997

Characterization of the mouse prostaglandin F receptor gene: a transgenic mouse study of a regulatory region that controls its expression in the stomach and kidney but not in the ovary.

BACKGROUND: The actions of prostaglandin F2alpha are mediated by a cell-surface receptor (FP), but little is known about the regulation of FP gene expression. To clarify the mechanisms underlying tissue specific transcription of the mouse FP gene, we isolated and characterized mouse genomic DNA clones encoding FP. RESULTS: Structural analysis revealed that the mouse FP gene is composed of three exons and two introns, and spans more than 11 kilobases. By primer extension and PCR analyses, the major transcription start site was identified as a cytosine nucleotide, but additional sites of transcription initiation were found in the ovary. There was no apparent difference in the FP gene transcription initiation site between the ovary, kidney and stomach. Sequence analysis of the putative promoter region showed only two potential SP-1 binding sites, but no other typical well-known consensus sequences. We generated transgenic mice with the potential promoter region of the FP gene connected to the lacZ reporter gene. Northern blot analysis showed that the pattern of expression of the transgene corresponded to that of FP expression, except in the ovary. Upon analysis by in situ hybridization, the lacZ gene transcripts were found to be expressed in the fundic glands in the stomach, and the cortical tubules in the kidney, in which endogenous FP transcripts were also expressed. On the contrary, expression of lacZ transcripts was not detected in the corpora lutea, where the highest expression of FP mRNA was observed. CONCLUSIONS: These studies suggest that a separate control mechanism exists for FP expression in the ovary, distinct from the expression in the stomach and kidney.

Amino Acid Sequence↗
PubMed1997

Brain tissue acidosis: effects on the extracellular concentration of N-acetylaspartate.

N-Acetylaspartate (NAA) is characterized by a high tissue-to-extracellular concentration ratio under normal conditions and is released from neurons during hypoosmotic cell swelling. As cell volume regulation and acid-base homeostasis share common processes, we have examined by microdialysis whether the extracellular concentration of NAA is altered by various acidotic challenges. Twenty-minute perfusion of 50 mM NH4+ through the microdialysis probe progressively lowered dialysate pH by 0.18, followed by a sudden, additional reduction after NH4+ removal. The latter effect indicated extrusion of cellular H+ because it was suppressed by blockade of Na+/H+ exchange with 5-(N,N-dimethyl)amiloride (1 or 5 mM in perfusion medium). NH4+ increased dialysate levels of NAA and lactate by approximately two- and threefold their initial values, respectively. These data demonstrate that pronounced intracellular acidosis is associated with NAA efflux, presumably from neurons. Whether this effect is linked directly to acid-base homeostasis or is secondary to acidosis-induced cell swelling remains to be clarified. Hypercapnia and perfusion of acid medium failed to increase dialysate NAA, probably because acidosis was not severe enough or the associated cellular swelling was not followed by regulatory volume decrease. As cellular swelling and acidosis are key features of cerebral ischaemia, further investigations into the role of NAA, and the development of sophisticated magnetic resonance spectroscopic methods capable of resolving intra-/extracellular NAA redistribution, would be especially relevant to clinical practice.

Acid-Base Equilibrium↗
PubMed1997

Thiobarbituric acid reactive substances are increased in the subcutaneous fat tissue of patients with end-stage renal disease.

BACKGROUND: Patients with end-stage renal disease are thought to be in a highly peroxidative state, based on studies showing decreased serum antioxidant activity and increased peroxidative products. In this study we confirm these findings by examining lipid peroxidation in subcutaneous fat tissue in uraemia. SUBJECTS AND METHODS: Twenty-seven subcutaneous fat samples were taken from patients with end-stage renal disease when they underwent intervention for arteriovenous fistula for haemodialyis or for catheter insertion for continuous ambulatory peritoneal dialysis. The control samples were taken from 11 patients with normal renal function and without any history of renal disease who had surgical interventions. Lipid peroxides were measured as thiobarbituric acid reactive substance. RESULTS: The concentration of thiobarbituric acid reactive substances in subcutaneous fat tissue in the patients with end-stage renal disease is 1.223 +/- 0.636 nmol/mg fat tissue (mean +/- SD) whereas the level in the control group is 0.097 +/- 0.054 nmol/mg fat tissue. A comparison of the two groups by Student's t test revealed a highly significant difference (P < 0.001). CONCLUSIONS: This study supports the finding of a severe peroxidative state in patients with end-stage renal disease.

Adipose Tissue↗
PubMed1997

Long-term efficacy of a self-retaining intraurethral catheter for the treatment of prostatic obstruction.

BACKGROUND: Transurethral prostatectomy is a standard treatment modality for infravesical obstruction with benign prostatic hyperplasia. However, some patients cannot undergo this procedure, so alternative devices or surgical procedures have recently been developed. METHODS: We treated 26 patients with prostatic outflow obstruction by placement of a self-retaining intraurethral catheter (IUC). All patients had coexisting medical complications which contraindicated transurethral prostatectomy. RESULTS: In the short-term, the treatment was successful in 96.2% of the patients, however, longer follow-up demonstrated a significant failure rate, and the 3-year success rate declined to 12.5%. The majority of late failures were associated with urinary tract infections. CONCLUSION: These results showed that although placement of an IUC to treat prostatic obstruction was effective in the short-term, its long-term efficacy was highly limited.

Aged↗
PubMed1997

Anisotropic repolarization in ventricular tissue.

Extracellular recording and stimulation techniques have been used to demonstrate that the effective refractory period of epicardial ventricular cells is significantly influenced by the sequence of activation. Whether myocardial fiber orientation is also important in determining the repolarization process is unclear. To determine the importance of fiber orientation on the repolarization process, we studied 12 blocks of pig right ventricular tissue in vitro. The size of each tissue block was 30 x 30 x 2 mm. Transmembrane action potentials were recorded, and effective refractory periods were measured from the preparation's epicardial surface, which showed nearly uniform fiber orientation. Tissues were paced at 500- and 1,000-ms cycle lengths. Sequential recordings were made at 1, 4, 7, 10, 13, and 16 mm from the stimulation site along and across the fibers. The results show that propagation of depolarization was much slower in the transverse direction than in the longitudinal direction. In the transverse direction, action potential duration was longest at the closest observation point, i.e., 1 mm from the stimulation, site (188 +/- 14 and 267 +/- 18 ms for 500- and 1,000-ms pacing cycle lengths, respectively). Action potential duration progressively shortened as the recording site was moved farther from the stimulation site (P < 0.001). The action potential duration 16 mm from the stimulation site was 165 +/- 11 and 247 +/- 12 ms for 500- and 1,000-ms pacing cycle lengths, respectively. In contrast, the action potential duration in the longitudinal direction did not change as the distance between the recording site and stimulation site increased. We conclude that, at physiological temperature and pacing cycle lengths, sequence of activation significantly influenced action potential duration when the propagation of activation was transverse to myocardial fiber orientation. When activation propagated parallel to fiber orientation, there was little or no change of action potential duration as distance increased.

Action Potentials↗
PubMed1997

Favorable effect of hemodialysis on decreased serum antioxidant activity in hemodialysis patients demonstrated by electron spin resonance.

There is considerable evidence that uremic patients are in a highly peroxidative state. The purpose of this study was to investigate the serum antioxidant activity that may regulate, or represent, the redox state in vivo. Serum from pre- and posthemodialysis patients and from healthy control subjects was added to a system generating the hydroxyl radical, and then the signal intensities of reactive oxygen species were measured by electron spin resonance and spin-trapping technique. The electron spin resonance signals of the reaction mixture containing prehemodialysis sera were significantly stronger than those of the reaction mixture containing healthy sera (P < 0.001, n = 19), and there was no significant difference in the signals between the reaction mixture containing posthemodialysis and healthy sera. These findings demonstrated that serum antioxidant activity in hemodialysis patients is significantly decreased, and this pathological condition is improved by hemodialysis treatment.

Adult↗
PubMed1997

[Gene diagnosis with an affinity sensor, BIACORE--principle and applications].

We are developing new techniques for detecting point mutations by DNA-DNA hybridization and DNA-protein interaction analysis with an affinity sensor, BIACORE. To detect point mutations by the hybridization method using synthetic oligonucleotides, we already found that the length of the probe and the location of mismatches were important. The PCR products of the N-ras gene derived from Hep G2 cells, which have heterozygous point mutations at codon 61 in the gene, were analyzed and the point mutations were detected with 13-mer probes. We suggest that the detection method using DNA-DNA hybridization is useful for detecting known point mutations. However, detect unknown mutations, E. coli mismatch recognition protein, MutS, was employed. All mismatches in immobilized 20 base pairs of double-strand DNA could be detected by MutS binding. We have started to apply of the MutS to the detection of point mutations in PCR products.

Bacterial Proteins↗